1. The problem statement, all variables and given/known data A rocket ship carrying passengers blasts off to go from New York to Los Angeles, a distance of about 5000 km. (a) How fast must the rocket ship go to have its own length shortened by 1%? (b) Ignore effects of general relativity and determine how much time the rocket ship’s clock and the ground-based clocks differ when the rocket ship arrives in Los Angeles. 2. Relevant equations Since I solved for (a) and got the correct answer (0.14c or approx. 4.2x107m/s), here is the equation for (b) that I used: T' = To/(sqrt(1-β2) alternate formula: t'2 - t'1 = ((t2 - t1) - (v/c^2)(x2 - x1)/(sqrt(1-β^2) 3. The attempt at a solution Total travel time = 0.119s (5E6/4.2E7) Velocity = 4.2E7 So: T' = 0.119/(sqrt(1-4.2E7^2/3E8^2)) This gave me 1.2E-1s (or about 120ms) alternately (second formula): T' = (0.119 - (4.2E7/c^2)(5E6)/(sqrt(1-(4.2E7^2/c^2))) This gave me 1.17E-1s (or about 120ms) --------------------------- It seems like both are giving me the same answer, but are off by a factor of 100 (since both round to 120ms and the correct answer is 1.2ms). Can someone please let me know where I'm going wrong?